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Mobile Phone Patent Abstract
A hands-free adapter for interfacing a mobile phone handset with
an existing audio system attaches to the handset by means of the
accessory connectors that are generally located on the bottom or
back of the handset. The adapter modulates the received audio from
an in-coming call with a pre-selected FM or AM carrier frequency,
and broadcasts the resulting, low power signal to the antenna of
a receiver of the existing audio system, which may include a home
stereo system, a portable stereo system, or a vehicle radio. The
receiver is tuned to the carrier frequency used by the adapter so
that the in-coming audio from the mobile phone can be heard over
the audio system speakers. For Radio Data System (RDS)-capable radio
receivers, a processor is provided within the adapter to generate
channel data, which is then transmitted with the carrier signal.
The RDS-capable radio receives the RDS signal and automatically
tunes itself to the selected channel. An optional processor can
be used to control internal and input/output signals through automatic
functions which may include volume control, frequency search, and
frequency tuning.
Mobile Phone Patent Claims
We claim:
1. An adapter for interfacing a handset with an audio system having
at least one speaker and at least one antenna for receiving an input
signal to an AM/FM radio, said handset having a transceiver for
receiving and decoding an incoming communication signal and for
encoding and transmitting an outgoing communication signal, said
handset further having a plurality of accessory connectors, said
adapter comprising:
a connection means for connecting the handset to the adapter, the
adapter receiving a decoded audio input signal from the handset;
a modulator circuit connected to said connection means, said modulator
circuit for receiving said decoded audio input signal and for providing
at least one level of modulation including modulation of said decoded
audio input signal with a carrier frequency, and for generating
an output signal comprising a modulated audio signal;
a transmission means for transmitting said modulated audio signal
to the at least one antenna of said AM/FM radio, wherein said modulated
audio signal is conducted to said at least one speaker;
a microphone connected to said connection means, said microphone
for receiving a user's speech and generating a microphone audio
output signal, wherein said microphone audio output signal is conducted
to said connection means and to said modulator circuit;
a processor cooperating with said modulator circuit for conducting
an automatic frequency search for an unused or a low-use frequency
of the audio system, wherein said processor generates a short pulse
to said modulator circuit and a modulated pulse is transmitted to
the AM/FM radio, and wherein the processor then monitors a received
pulse signal for the return of the short pulse via said microphone,
and wherein the pulse is repeated over a sequence of AM and FM frequencies
until said processor verifies the received pulse signal; and
a power input means for providing at least one operating voltage
to said modulator circuit, said transmission means and said microphone.
2. The adapter as in claim 1, wherein said processor includes means
for producing RDS data.
3. The adapter as in claim 2, wherein said at least one level of
modulation further includes a subcarrier modulation for modulating
said RDS data on a subcarrier frequency.
4. The adapter as in claim 1, wherein said processor includes automatic
volume control capability for automatically controlling an audio
volume, wherein the processor utilizes the audio output signal from
the microphone to measure the noise level in the vehicle and sets
a gain of the output signal.
5. The adapter as in claim 1, wherein said transmission means comprises
a circuit having a power amplifier and a transmitting antenna for
amplifying and transmitting said modulated audio signal to said
receiving antenna.
6. The adapter as in claim 1, wherein the at least one antenna
of the AM/FM radio further includes a receiving antenna connector,
and wherein said transmission means comprises:
an RF cable connector connected to said modulated audio signal;
and
an external RF cable for connecting said RF cable connector to
said receiving antenna connector.
7. The adapter as in claim 1, further comprising support means
disposed on a fixed surface for releasably supporting said handset.
8. The adapter as in claim 7, wherein said support means comprises
a cradle for receiving the handset and having said connection means
fixedly disposed therein.
9. The adapter as in claim 8, wherein said electrical connection
means includes means for connecting said power input means to said
handset for powering said handset.
10. The adapter as in claim 1, wherein said handset further comprises
a display screen, and said adapter further comprises an RDS receiver
circuit for receiving an external radio signal containing RDS data,
wherein said RDS receiver circuit is connected to said processor
for communicating said RDS data for display on said display screen
of said handset.
11. The adapter as in claim 10, wherein the processor further provides
an automatic frequency tuning operation for tuning said at least
one receiving means to a frequency channel indicated within said
external radio signal.
12. A method for interfacing a handset with an audio system for
hands-free operation, wherein the handset includes a transceiver
for receiving and transmitting communication signals, a display
screen, a microphone for receiving audio signals, and a plurality
of accessory connectors, and the audio system includes an RF receiver
pre-tuned to an unused frequency and at least one speaker, the method
comprising:
(a) initializing a search frequency;
(b) transmitting a search signal on the search frequency to said
RF receiver;
(c) waiting a pre-determined time to receive the search signal
via said microphone;
(d) if the search signal is received by said microphone, then adjusting
said carrier frequency to match said search frequency;
(e) if the search signal is not received, then adjusting the search
frequency;
and
(f) repeating steps (b)-(e) until the search signal is received
by the microphone; and
(g) when the search signal is received by said microphone:
(h) converting, within said transceiver, an incoming communication
signal including a speech signal into an audio input signal;
(i) modulating an RF carrier signal with said audio input signal
to generate a modulated audio signal corresponding to said speech
signal;
(j) transmitting said modulated audio signal to said RF receiver
so that said speech signal may be played over said at least one
speaker.
Mobile Phone Patent Description
FIELD OF THE INVENTION
This invention relates generally to accessories for mobile telephones,
and more specifically to an apparatus and method for interfacing
a mobile phone with an existing audio system for hands-free use
of the mobile telephone.
BACKGROUND OF THE INVENTION
Mobile phone use is pervasive in today's society including use
in the home, at work, and in the car. The use of a mobile phone
while operating a motor vehicle typically involves holding the mobile
phone handset in one hand while using the other hand for steering,
shifting gears, adjusting the radio volume, or any of a number of
activities. The distraction of handling a mobile phone while driving
poses a threat to the safety of the driver and others in the vicinity
of the driver and vehicle. Studies have equated driving while using
a mobile phone with driving under the influence of alcohol or drugs
in terms of the number of accidents caused. Legislation is being
considered or has already been enacted in many countries banning
the use of hand-held mobile phones while driving. In the United
Kingdom, for example, penalties for using such a mobile phone while
driving, even if no accident results, can include imprisonment and/or
a substantial fine.
Solutions to this problem have appeared in the form of mobile phone
hands-free systems. Some automobiles are equipped with a mobile
phone hands-free system during manufacture. These systems may integrate
a mobile phone with the car audio system, such as the system disclosed
in U.S. Pat. No. 5,243,640 of Hadley et al., which is incorporated
herein by reference. Hadley's invention describes an interface that
effectively shares an output transducer and amplifier between an
audio system and a phone in a vehicle. The advantage of this system
is clear if it is installed in the car during manufacture. However,
drivers of vehicles without this feature who, nonetheless, desire
to have the hand-free convenience must have an aftermarket system
installed into their vehicles at a cost which may be substantial.
Further, an aftermarket installation in a vehicle can often effect
the aesthetics of a vehicle interior which was not expressly designed
to receive such an installation. Another disadvantage is that the
system, as described, is not portable. As a result, a similar system
must be installed into every audio system that is used by the mobile
phone owner.
An alternate solution for providing hands-free phone operation
is in the purchase and use of a mobile phone hands-free kit. These
kits are portable and require very little, if any, installation.
Such kits, which may have their own audio amplifier and speaker(s),
are usually compact, and thus, the audio output of the speakers
is typically "tinny". Further, increasing the volume of
such speakers to a level sufficient to hear a soft-spoken person
at the other end of the connection while in a noisy background can
result in distortion of much of the conversation. In contrast, a
vehicle's existing audio system, which may be factory-installed
or an aftermarket addition, is often sophisticated and of high sound
quality, capable of sustaining increased volumes without distortion.
Even the most basic audio system that is installed during manufacture
of a vehicle avoids the high, thin and metallic sound quality that
is present in many currently available hands-free kits.
The interfacing of separate audio components into a vehicle audio
system is known. In one example, the use of an automobile audio
system for portable Compact Disk (CD) players is disclosed in U.S.
Pat. No. 5,319,716 of McGreevy, which is incorporated herein by
reference. The wireless radio adapter described therein accepts
the stereo signal of a CD player, via an audio-out jack, and transmits
a stereo FM (Frequency Modulation) signal to a conventional automobile
FM radio. The adapter is configured to accept the right and left
stereo inputs of a playback device, and does not have the capability
to accept audio from a mobile phone. Further, the McGreevy adapter
does not provide a plurality of automatic functions via the use
of an internal processor.
In view of the failure of the prior art to provide a solution,
the need remains for a means for readily interfacing a mobile phone
with an existing audio system, such as in a vehicle, which is economical,
portable, and easy to install. Further, it would be desirable to
provide a "smart" device that accepts audio from a mobile
phone, provides optional receive and transmit functions, and interfaces
with an AM or FM receiver of an audio system by means of a low power
RF signal transmission.
SUMMARY OF THE INVENTION
It is an advantage of the present invention to provide a portable,
hands-free interface between a mobile phone and any of a plurality
of audio systems including audio systems in a vehicle, a home, and
a boat.
It is another advantage of the present invention to provide an
economical accessory kit that can interface a standard mobile phone
to any audio system that has an AM or FM radio receiver, cassette
player, or auxiliary audio input.
Still another advantage of the present invention is to provide
a "smart" interface having a plurality of functions through
the use of an internal processor.
Yet another advantage is to provide means for easy installation
of the interface into the vehicle which does not require significant
modification to the vehicle interior to attach extraneous accessories.
In an exemplary embodiment of the present invention, a hands-free
adapter attaches to a mobile phone handset by means of the accessory
connectors that are generally located on the bottom or back of the
handset. The adapter modulates the received audio from the in-coming
call with the pre-selected FM or AM carrier frequency, and broadcasts
the resulting, low power signal to the antenna of a receiver, which
may include a home stereo system, a portable stereo system, or a
vehicle radio. The receiver is tuned to the carrier frequency used
by the adapter so that the in-coming audio from the mobile phone
can be heard over the vehicle's audio system. For Radio Data System
(RDS)-capable radio receivers, a processor is provided within the
adapter to generate channel data, which is then transmitted with
the carrier signal. The RDS-capable radio receives the RDS signal
and automatically tunes itself to the selected channel.
The user's speech is picked up by a high frequency microphone that
plugs into the adapter and which is placed in relatively close proximity
to the user's mouth. The detected speech is amplified and sent to
the mobile phone via an audio out signal line, where it is modulated
and transmitted as part of the mobile phone's normal operation.
Power sources for the circuitry in an adapter include a mobile
phone battery, or a vehicle or another external battery. To conserve
battery power, the adapter processor monitors whether the phone
is the "call mode" and transmits or ceases transmission
to the vehicle radio accordingly. This "ON/OFF mode" processor
function conserves the handset's battery power.
In an alternative embodiment of the present invention, the system
has the additional feature of a built-in Radio Data System (RDS)
radio receiver and FM radio. The RDS radio receives RDS data which
is sent to the mobile phone for display on the screen of the mobile
phone. This enhanced system also allows the user to use the phone
as an FM radio. A connector on the adapter provides a connection
for headsets or earphones.
In yet another embodiment of the present invention, the above described
systems, with and without the RDS receiver and FM radio, are built
into the holder/cradle of the mobile phone handset, eliminating
the need for a separate adapter.
For situations where a decreased RF output is highly desirable,
for example, where the user wishes to minimize the chance of the
signal being picked up by other near-by radios, a hard-wired embodiment
of the hands-free interface may be installed. In a hard-wired embodiment
of the present invention, the modulator which is in addition to,
or part of, the adapter assembly is installed between the vehicle
radio and the vehicle radio antenna. An RF cable connects the modulated
RF audio signal to the antenna of the vehicle radio. The hard-wired
embodiment significantly reduces the required power of the signal
and possibility of stray transmission.
In still another embodiment of the present invention, the adapter
makes use of one or more cables to establish an interface from the
mobile phone to the vehicle's audio system. One type of cable interface
makes use of a cassette player, which is included in many vehicle
audio systems. For example, as disclosed in U.S. Pat. No. 4,734,897
of Schotz, which is incorporated herein by reference, an adapter
is formed in the general shape of a cassette tape which houses a
recording head positioned to contact the playback head of a cassette
player. The adapter is used as an interface from the headphone jack
of a playback device, such as a compact disk player, to the cassette
player audio system. In this embodiment an audio "out"
circuit and a jack which interfaces the adapter to the plug of the
above described cassette adapter may be provided. An alternative
type of cable interface may be used to connect the adapter directly
to audio input jacks that are commonly present on vehicle radios,
CD players, and/or cassette players.
BRIEF DESCRIPTION OF THE DRAWINGS
Understanding of the present invention will be facilitated by consideration
of the following detailed description of preferred embodiments of
the present invention taken in conjunction with the accompanying
drawings, in which like numerals refer to like parts, and in which:
FIG. 1 is a block diagram that illustrates the overall concept
of a Mobile Phone Hands-Free Interface of the present invention;
FIG. 2 is an electrical schematic illustrating a circuit configuration
of a Mobile Phone Hands-Free Interface according to a first embodiment
of the present invention;
FIG. 3 is an electrical schematic of a second alternate embodiment
of the interface circuit having an RDS Receiver/FM Radio and related
circuitry;
FIG. 4 is a schematic diagram of a third alternate embodiment of
the interface;
FIG. 5 is a block diagram showing an embodiment using the alternative
interface means of a cassette player accessory, and an auxiliary
audio input cable accessory;
FIG. 6 is a block diagram showing a hard-wired embodiment; and
FIG. 7 is a perspective view of a handset cradle for use in the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following detailed description utilizes a number of acronyms
which are generally well known in the art. While definitions are
typically provided with the first instance of each acronym, for
convenience, Table 1 below provides a list of the acronyms and abbreviations
and their respective definitions.
TABLE 1 ______________________________________ ACRONYM DEFINITION
______________________________________ AFS Automatic Frequency Search
AFT Automatic Frequency Tuning AM Amplitude Modulation AVC Automatic
Volume Control DAF Detected Audio Frequency FM Frequency Modulation
HF High Frequency PLL Phase Locked Loop RDS Radio Data System RF
Radio Frequency ______________________________________
Referring to FIG. 1, a conventional mobile phone handset, which
is generally designated by reference numeral 1, is connected to
an accessory adapter 2 by placing it in a specially-designed cradle
50 or other support means which provides an electrical connection
between the mobile phone handset 1 and adapter 2. Details of exemplary
means for connection are shown in FIG. 7, in which is illustrated
cradle 50 comprising a substantially four-walled housing into which
the phone handset 1 (not shown) may be inserted. Cradle 50 includes
means for hanging on a fixed surface such as a car dashboard or
center console. In the example shown, keyhole 54 may be used for
hanging on a screw or peg. Cradle 50 may also be attached using,
for example, an adhesive means or hook-and-pile fastener, or may
have a clip for hanging on an existing structure on the fixed surface.
At the inside bottom surface 56 of cradle 50 are electrical connectors
58 which are adapted to mate with the accessory connectors of handset
1 when the handset is inserted therein. The accessory connectors
may include audio input and output means and an attachment for an
external power supply. Depending on the configuration of the handset,
positioning of the electrical connectors 58 may vary. In a preferred
embodiment, the electronic circuitry hereinafter described will
be housed within casing 57 at the lower portion of cradle 50, with
at least one connector for attachment of the input wiring from microphone
51 and other external input/output devices.
Referring again to FIG. 1, the adapter 2 receives a detected audio
frequency (DAF) signal from the mobile phone, and subsequently modulates
and transmits the signal on a low power, RF carrier. This signal
is received by an AM or FM radio 3 via the existing antenna of the
radio 4, and output through the vehicle's existing speakers 21.
The adapter 2, or alternatively the phone handset 1, provides a
connection for a high frequency (HF) microphone accessory 51 which
may be attached to a visor, steering wheel, or some other place
in a proximity to pick-up the handset user's speech.
FIG. 2 illustrates the basic circuitry of the hands-free audio
system interface. In the first embodiment of the present invention,
the interface comprises of power circuitry 11, a processor 6, a
high frequency (HF) amplifier 10 for an HF microphone 13, a DAF
attenuator 9, a modulator circuit 7, a power level controller 8,
and an antenna 16.
The power circuitry 11 generates operating voltages for the electrical
components of the adapter. The source voltage for this circuitry
is input through the accessory connector 5 via the input voltage
line 12. The source voltage is derived from a battery within the
adapter, or may be provided by an independent source outside of
the adapter such as, but not limited to, the mobile phone battery
or the vehicle battery.
The detected audio frequency (DAF) waveform 15 from the mobile
handset 1 is fed into the adapter 2 through the accessory connector
5. The audio waveform passes through the DAF attenuator 9 that,
together with the processor 6, comprises an audio modulation level
controller. The processor, which determines level control parameters
and other adapter functions, receives information from the mobile
phone via the serial communications bus 14. Audio modulation level
control may be attained automatically by automatic volume control
(AVC). Automatic volume control is provided via the processor 6
which uses the audio input from HF microphone 13 to measure the
noise level in the vehicle, and sets the gain of the DAF attenuator
9 accordingly.
The attenuated DAF signal is fed into the remaining RF transmission
circuitry, which is generally represented in FIG. 2 by a crystal
oscillator 17, a modulator circuit 7, which includes a phase-locked
loop (PLL) to maintain the carrier at the correct frequency, and
a power amplifier 8. The AM or FM modulated signal is transmitted
though the antenna 16 and is received by the AM or FM radio of the
vehicle. The processor 6 is used to set the carrier frequency of
the modulator 7 and control the gain of the power amplifier 8. The
anticipated low power output of the RF signal will comply with the
FCC regulations for intentional radiators. (The appropriate FCC
regulations are generally known to those skilled in the art.)
The modulator 7 frequency may be pre-set by the user using the
selection function of the mobile phone handset 1 menu, or may be
set automatically. The HF microphone feedback circuitry 13, 10 to
the processor 6 provides the capability of automatic frequency search
(AFS). The processor 6 generates a short pulse to the modulator
7, and the modulated pulse is transmitted to the vehicle's radio
via the antenna 16.
The processor 6 then monitors the received signal for the return
of the pulse via the HF microphone 13 and HF amplifier 10. This
process is repeated over a sequence of AM and FM frequencies either
serially, or based on pre-set frequencies, until the carrier frequency
matches the tuned frequency of the vehicle. When the frequencies
match, the HF microphone 13 picks up the feedback audio and the
processor 6 stops the scanning and lock on to the desired frequency.
Another function of the processor 6, the ON/OFF control, is to
terminate transmission when the phone is not in the "call mode"
to conserve the handset's battery power.
In an embodiment of the adapter for interface with an RDS-compatible
radio, the processor 6 may also provide the additional function
of generating Radio Data System (RDS) data for transmission to the
RDS vehicle radio. As is known in the art, RDS is a digital information
system which transits data modulated on a subcarrier to RDS capable
FM radio receivers. The data contains information such as program
service, clock time, and radio text that may be viewed on the radio
display, as well as data that can be used by the radio to provide
automatic functions such as volume control and frequency tuning.
The RDS data is sent in sequences called groups where each group
type comprises 4 blocks of 26 bits each, consisting of a 16 bit
information word followed by a 10-bit check word. The specification
for RDS, incorporated herein by reference, is described in European
Standard CENELEC EN 50 067 (April 1992), "Specification of
the radio data system", and in NRSC United States RBDS Standard
Jan. 8, 1993, "Specification of the radio broadcast data system".
The transmitted RDS data does not affect the operation of a normal
vehicle radio.
The processor 6 and modulator circuitry 7 of the exemplary embodiment
may be designed to include RDS capability that will provide the
mobile phone user with a plurality of functions including automatic
frequency tuning (AFT) of the RDS vehicle radio. When a call is
received or made, the processor 6 generates RDS data which includes
alternate frequencies (AF) information within Group Type OA and
Enhanced Other Networks (EON) information within Group Type 14B,
as described in the aforementioned European and United States standards.
The RDS data from the processor 6 is introduced into the modulator
circuitry 7 where it is modulated with the subcarrier, then transmitted
with the modulated audio signal to the RDS vehicle radio. The AF
and EON information is used by the RDS vehicle radio, in accordance
with the standards, to automatically tune the radio to the desired
channel.
An alternative embodiment of the invention, illustrated in FIG.
3, a variation of the embodiment of FIG. 2, includes the addition
of an RDS FM radio receiver 18. The receiver 18 can receive RDS
data and relay the information to the processor 6, which, in turn,
communicates the information via the communications bus 14 to the
display screen of the mobile handset 1. An audio amplifier 19 and
a connection for a headset, earphones 20 or other type of listening
device, allow the user to listen to the RDS FM radio receiver. Inclusion
of an RDS FM radio into the adapter provides a convenient RDS information
display means through use of the mobile phone handset display without
having to buy and install additional or replacement equipment for
the vehicle audio system.
In another embodiment illustrated in FIG. 4, a basic adapter accepts
a detected audio frequency (DAF) signal 15 from the mobile handset
1 through the accessory connector 5, modulates the signal, and transmits
the signal through the antenna 16 to the vehicle radio. The oscillator
and modulator circuitry 25 of this embodiment comprises standard
FM transmitter circuitry that is well known in the art, and a manual
tuner for the transmission frequency. The audio signal from the
HF microphone 13 is amplified 10 and sent to the mobile handset
1. The source voltage for the operating voltage circuitry 11 is
input through the accessory connector 5 via the input voltage line
12.
FIG. 5 illustrates alternative embodiments of the adapter that
make use of one or more cables to establish an interface to the
automobile's audio system. The detected audio frequency (DAF) signal
from the mobile phone handset 1 is input through the mobile phone
accessory connector 5, amplified, and output to a standard "audio-out"
jack 35 located on the adapter 2. The adapter "audio-out"
jack 35 accepts a standard audio plug 34, and thus, the adapter
2 may then be used with a number of cable devices to interface the
audio signal from the mobile handset 1 to electronic equipment 36,
such as a cassette player or CD player, that makes use of an audio
system. Referring to FIG. 5, two types of accessory cables are shown
to exemplify a variety of different cable interfaces that may be
used with the adapter 2. The two cables 31, 32 are alternative cable
interfaces, and are not intended for use in combination. The first
alternative interface employs a cassette player adapter-cable 31
as disclosed in U.S. Pat. No. 4,734,897 of Schotz, referenced above,
and the second alternative interface makes use of a standard plug-plug
cable 32 to complete the connection to an auxiliary audio input
33 that may be available on the installed electronic equipment 36.
An alternative embodiment having a hard-wired configuration is
illustrated in FIG. 6. The hard-wired embodiment employs an RF cable
46 to transmit an injected RF signal from the output of an external
modulator 44 to an RF connector of the radio receiver antenna 4.
Audio and control signals are supplied to the external modulator
44 via an accessory jack and cable 40, 42.
The preferred embodiments as described herein provide a means for
hands-free use of a mobile phone handset via an interface that is
portable and wireless, that does not require disruptive or costly
installation, and that makes use of an existing audio system. Such
an interface provides the improved safety of hands-free operation
while providing high quality sound to enhance the intelligibility
of the received speech. While the invention is particularly described
in its applicability to facilitating the use of mobile phones in
vehicles, other uses are anticipated, including, for example, the
use of the interface with a portable stereo can provide a portable
speaker phone for conference calls, even while the user is out of
his or her office, or can allow a user to set up an impromptu speaker
phone at home using a home stereo system.
It will be evident that there are additional embodiments which
are not illustrated above but which are clearly within the scope
and spirit of the present invention. The above description and drawings
are therefore intended to be exemplary only and the scope of the
invention is to be limited solely by the appended claims. |